It is standard to mount a railroad track to a substrate by means of a metallic mounting assembly that holds the track down while permitting at least limited movement transverse of the longitudinal extending of the track. Such assemblies must be exceptionally rugged and have very long service lives, while still being subject to mass production at a reasonable unit cost since they are used in vast numbers.
The amount of give of such an assembly can be controlled by making it of two members or plates and providing an elastomeric cushion or lining between them. The track is directly secured to the track plate, the base plate is directly secured to the substrate, and the lining permits some relative movement of the two plates. While this works fairly well, it is difficult to adjust the resistance to displacement of the rail longitudinally, vertically, and transversely. In particular it is frequently necessary to provide completely different degrees of resistance transversely and longitudinally, as the transverse and longitudinal loads the track fastener is subjected to vary significantly.